[Mesa-dev] [RFCv0 0/8] gallium: add support for NIR as alternate IR

[Marek Olšák]

On Tue, Oct 20, 2015 at 2:37 PM, Rob Clark <robdclark at gmail.com> wrote:
> On Tue, Oct 20, 2015 at 6:49 AM, Marek Olšák <maraeo at gmail.com> wrote:
>> On Tue, Oct 20, 2015 at 3:51 AM, Rob Clark <robdclark at gmail.com> wrote:
>>> On Mon, Oct 19, 2015 at 8:53 PM, Marek Olšák <maraeo at gmail.com> wrote:
>>>> Yes, drivers need to "dup" tokens if they want to keep them. Their
>>>> lifetime is the create function and that's it. st/mesa only keeps the
>>>> tokens for vertex shaders, because it needs for emulating some
>>>> features with the Draw module.
>>>
>>> It is something that I think would be worth revisiting, since the
>>> common case is that drivers have to dup the tokens to do their own
>>> variant mgmt.. so that seems like the better case to optimize for.  I
>>> think the only one that isn't doing it's own variant mgmt is nouveau,
>>> but Ilia mentioned at some point that there where some edge cases
>>> where they really do need a variant.
>>
>> This would add more cruft into state trackers and modules. Doing "dup"
>> in the driver is the easiest way to handle this.
>>
>> Also, drivers should be able to release any incoming IR if they don't
>> need it. Including NIR. Having a requirement that some IR must be in
>> memory for the lifetime of shaders is just overall a bad idea.
>
> If you need to create variants, you need to hang on to the IR until
> all possible variants are created (ie. forever)

Not true. You can convert to another IR, run lowering passes, and keep
the result of that.

Marek